Three sets of studies comprise the experimental objectives. The first series of studies continues an exploration of the meaning of dysfunctions of smooth pursuit eye movements in schizophrenic patients and their relatives. Twin studies, effects of psychotropic drugs, longitudinal course of the dysfunction and normal population mapping will be undertaken. The 2nd and 3rd sets of studies focus on the effects of pychotropic medication on measures of thought disorder and on specific tests of cognition and perception used in cognitivecontrol studies.